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Louder Passive Electronics


stuartah

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I think you will find that in the real world you are not getting nice constant sine wave signals out of signals, excessive times to charge up those caps and then farting when the supply falling below as the signal decays...there seem to be quite a few fundamental flaws and what you appear to be getting from a sine wave is effectively a squarewave een in an ideal world with a very simple signal and constant form and with both pickups feeding it. Reality is simply not like that...massive changes between a big low chord and a high single not, huge changes as the frequencies increase...and you are working with AC signals and the caps will pass most of this rather than store them.

In the end that is a lot of electronics stuffing up the signal, all of which will rob from the actual output to the guitar and take from the "tone" and all apparently to avoid a battery...I still fail to see the point other than to avoid a battery, but you are adding so much stuff in there anyway you would need the kind of space in the guitar that a battery would take anyway as far as I can see.

Sorry if I sound too negative, but there comes a time to solder up an experiment and see what really happens.

Still...good to think about such things...you're not the first...and perhaps you may come up with some ideas from it that might well be worth pursuing more...

pete

Yeah, thanks ^^

But the idea was just to simply give it a "beefier" sound not actually send it into OD every time it ran. The thought also was to put it into a DPDT switch design so you wont always have that OD signal.

My original design I think will somewhat work, but the beefing section is so little and like you pointed out its hard to measure the out put on a changing signal since the computer hates variable.

The one thing I did notice was that when removed the DC output slowly decase as it also slowly rises.

The main thing for this was to simply give a player something play around with like for a solo or something. And the other reason was the thought of the whole battery thing. The "nothing comes for free" saying applied here by taking more room in the guitar by never having to replace the batteries into a small compartment.

Edit: I just noticed this, and I've been working with op-amps for a year now, but the voltage output at the rectifiers is directly proportional to the resistor in the feedback loop on the op-amp

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I think you will find that in the real world you are not getting nice constant sine wave signals out of signals, excessive times to charge up those caps and then farting when the supply falling below as the signal decays...there seem to be quite a few fundamental flaws and what you appear to be getting from a sine wave is effectively a squarewave een in an ideal world with a very simple signal and constant form and with both pickups feeding it. Reality is simply not like that...massive changes between a big low chord and a high single not, huge changes as the frequencies increase...and you are working with AC signals and the caps will pass most of this rather than store them.

In the end that is a lot of electronics stuffing up the signal, all of which will rob from the actual output to the guitar and take from the "tone" and all apparently to avoid a battery...I still fail to see the point other than to avoid a battery, but you are adding so much stuff in there anyway you would need the kind of space in the guitar that a battery would take anyway as far as I can see.

Sorry if I sound too negative, but there comes a time to solder up an experiment and see what really happens.

Still...good to think about such things...you're not the first...and perhaps you may come up with some ideas from it that might well be worth pursuing more...

pete

Interesting idea. But, I have to agree with Pete on all points. If you build it, I think the real world end result will be completely different from what you are simulating. It would be an interesting experiment in any case.

The other thing is that it will have massive distortion according to your oscilloscope screenshot. Those sine waves have been practically turned into square waves. It seems to me that it will sound a lot like a very muddy sounding Fuzz Face type circuit with a low output.

Edited by Paul Marossy
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Interesting idea. But, I have to agree with Pete on all points. If you build it, I think the real world end result will be completely different from what you are simulating. It would be an interesting experiment in any case.

The other thing is that it will have massive distortion according to your oscilloscope screenshot. Those sine waves have been practically turned into square waves. It seems to me that it will sound a lot like a very muddy sounding Fuzz Face type circuit with a low output.

That is very true, but at a 500ohm or less for the negative feedback loop, you get a nicer more "beef" sound if you will more or less you get it to that DS area in which there's only distortion when the peaks hit their highest for the voltage output along that line I'm getting someone who has the ability to actually make this mess with it.

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solo frequencies:

amperageopampadder2.png

to the left of the circuit looks very interesting, but i'm lost, looking at everything east of those diodes (that could be attributed to a sloppy schematic, or the fact that I don't know what the 4 plugs are on an oscilloscope). I guess my first question is, why so many capacitors? They are all in parallel, so can't you just figure the equivalent capacitance and use one big cap?

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to the left of the circuit looks very interesting, but i'm lost, looking at everything east of those diodes (that could be attributed to a sloppy schematic, or the fact that I don't know what the 4 plugs are on an oscilloscope). I guess my first question is, why so many capacitors? They are all in parallel, so can't you just figure the equivalent capacitance and use one big cap?

The number of caps is to make sure that all the frequencies are taken out and moved to a near flat line voltage. Caps in parallel add and the fact that when the signal is removed the caps discharge slower and allows for time to pick the next note, rather than having an instantaneous discharge would could harm the op-amp or other components. But the real answer is having one small cap would not cut out the low frequencies and in fact would block them from having a proper charge. The zener diodes are their to help the caps sustain that voltage for when the signal dips below the negative line.

Basically the number of caps are their to act as a sustaining tool

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to the left of the circuit looks very interesting, but i'm lost, looking at everything east of those diodes (that could be attributed to a sloppy schematic, or the fact that I don't know what the 4 plugs are on an oscilloscope). I guess my first question is, why so many capacitors? They are all in parallel, so can't you just figure the equivalent capacitance and use one big cap?

The number of caps is to make sure that all the frequencies are taken out and moved to a near flat line voltage. Caps in parallel add and the fact that when the signal is removed the caps discharge slower and allows for time to pick the next note, rather than having an instantaneous discharge would could harm the op-amp or other components. But the real answer is having one small cap would not cut out the low frequencies and in fact would block them from having a proper charge. The zener diodes are their to help the caps sustain that voltage for when the signal dips below the negative line.

Basically the number of caps are their to act as a sustaining tool

Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

Edited by Paul Marossy
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Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

The caps held sustain while the one of the zener models is effectively a battery. In this circuit the zener diode draws more and more current to boost the circuit to that 10v mark in this case. While it may be that you wont need the 10v always there it is simply to force the circuit to have a supply for the op-amp.

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Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

The caps held sustain while the one of the zener models is effectively a battery. In this circuit the zener diode draws more and more current to boost the circuit to that 10v mark in this case. While it may be that you wont need the 10v always there it is simply to force the circuit to have a supply for the op-amp.

yeah, but the "breakdown voltage" of a 5V zener diode is 5V. Where is that circuit ever going to see 5V from passive guitar pickups that only output an instantaneous max. of of 2V PTP?

You need to have it built because I think your circuit simulator in this case is not a reflection of the real world.

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Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

The caps held sustain while the one of the zener models is effectively a battery. In this circuit the zener diode draws more and more current to boost the circuit to that 10v mark in this case. While it may be that you wont need the 10v always there it is simply to force the circuit to have a supply for the op-amp.

yeah, but the "breakdown voltage" of a 5V zener diode is 5V. Where is that circuit ever going to see 5V from passive guitar pickups that only output an instantaneous max. of of 2V PTP?

You need to have it built because I think your circuit simulator in this case is not a reflection of the real world.

Like I said earlier, there's a half a second of charging period, where the zenor charges up to the voltage its set to. Zener diode will pull as much current it needs to charge to its break down point

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also, besides trying this for the signal output, it'd also be interesting to apply it to some lights on your guitar, like the old rickenbacker guitars

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I really think there are some fatal flaws between the virtual ideal situation and the reality of guitar signals and resulting outputs. Also not anticipating the effect on the guitars sound and output by diverting power from the output to charge up caps and run electronics, let alone lights. It is easy enough to use the signal as a trigger for lights and effects (like and auto-wha for instance) but to use the power to run lights itself is really over reaching.

Guitar signals are not analogous to constant sine waves. They can put out a bit of power but generally only at a sharp spike for a micro second at the start of the note after which it quickly drops off. They are also complex AC wave forms that vary greatly with pitch and picking strength. None of which bodes well with audio electronics that require a very constant regulated DC power supply to avoid noise and distortions, or even to work properly at all.

A further misunderstanding may well be in the attraction of "active pickups" put in the topic title. The popularity of this sound is that it is clear, even and powerful...may regard the sound as "sterile" compared to passive pickups. However, they do take effects and distortions and overdrive amps well due to their extreme clarity and eveness of harmonic content and output.

Contrast this with the apparent output even in the ideal virtual world of this proposal. At best and extremely squared off wave form that is likely to be somewhat ugly and abrasive and certainly not the kind of clarity that people seek in active electronics.

The ideas are interesting to consider but largely because of it's failings. With such things it may well require stepping back and asking what is trying to be achieved. If it is motivated entirely as an aversion to battery installation, then there is a major flaw. You could get some of the benefits of active electronics with passives like low impedance pickups perhaps boosted by transformers. But it is not enough just to get signal strength but also a good sound. Les Paul's recording model and some lace pickups use this strategy for instance, but neither have enjoyed widespread popularity for their sound.

...

However, such things are interesting to consider in the wider world. For instance, such a charged cap scheme could be used in a water supply to generate power by running over piezo elements and ionizing water as it runs through a pipe. I don't even know if that is a desirable thing, but perhaps a more suitable application of such ideas.

I have been criticized myself for appearing down on modeling electronics, perhaps because I have little experience skill or ability to interrupt the results...but from experience, it is only with at least some experimentation to prove the concept in the application or in general that you can really get an idea of the pitfalls and complexities. Modeling using constant waves is always going to be an "ideal" and give false results IMHO. And in audio, a lot depends on what it actually sounds like and issues of distortions and noise...A higher output is never going to be desirable even if possible if it sounds ugly.

Anyway just a few thoughts. Lights take a lot of power as people have discovered from doing various light effects around here and there are all kinds of switching issues/noise to consider as well.

pete

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I know what you mean, and I'm working on getting a pickup design for multisim, but for now all I've been able to do is test the various signals and test the charge times

When I get a more real source, or I actually have the ability to test this as a real world circuit, we can pick this up again. but the one thing to remember, I put those transistors in there so as not overload the source.

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This is a great idea to play with but it really, really (really) wont work. When you build it you will see, so it would be best to build it soon so you find out. There is not enough energy available from the string via pickups to drive the circuits that you need.

In any case, for about $2 in parts you can build a single JFET active stage that gives you a high quality, low impedance boosted output, and run on a small battery that will last for thousands of hours.

Sorry to be negative - if you do make it work you can have more fun trashing this post!

John

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  • 2 weeks later...
So...have you tried this only in a virtual world...or have you actually tried this?

I've only done this in virtual, but in theory it works, and when I measured the components the amperage maxes about 1mA

Next, anyone remember the ideal model of a zener diode? I kicked the two virtual zeners up to about 20v and dang it kicked the amps up to about 2mA and looking at the output it just blasted that thing to kingdom come

This project sounds wishy-washy at best and I'm not getting this part at all. Zeners regulate voltage down, not up, at least that's what I was taught.

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Like I said earlier, there's a half a second of charging period, where the zenor charges up to the voltage its set to. Zener diode will pull as much current it needs to charge to its break down point

No, I think you are confused on the zener's mode of operation. If you give a 5 volt zener 3 volts, you will get 3 volts max. I do not think there is a way to get 5 volts.

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Like I said earlier, there's a half a second of charging period, where the zenor charges up to the voltage its set to. Zener diode will pull as much current it needs to charge to its break down point

No, I think you are confused on the zener's mode of operation. If you give a 5 volt zener 3 volts, you will get 3 volts max. I do not think there is a way to get 5 volts.

+1 on confused.

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